I have completed the connection of Geberit to MVHR, so here is the detail FYI. There seemed to be interest in the JSH and PeterW versions. Plasterboarding and second fix is delayed, so the fans are not yet functioning, so the ventilation performance is as yet unconfirmed.   Geberit model #111.353.00.5 has a Y-branch for extraction of air[smells]. I removed the translucent plastic duct [part of the Geberit] attached to the Y, cut off and Siga taped up the end that l